<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

<form action="/calc/PostSum"  method="post" >
  a <input type="number" name="a" value=""><br>
  b <input type="number" name="b" value=""><br>
  <input type="submit"  value="提交" >
</form>
</body>
</html>